This invention relates to an intake structure for a V-type engine and more particularly to an improved tuned induction system for such engines.
It has been the general practice with V-type engines to position the induction system at least in part in the valley between the cylinder banks. This provides a generally compact engine construction. However, there are some disadvantages with such an arrangement, particularly where the induction system is of the tuned or variable tuned type.
Because of the fact that the induction system is so instrumental in determining the performance of the engine and since conventional induction systems are designed primarily to serve most efficiently one engine speed or load range, it has been proposed to use so-called variable induction systems. These systems provide an effective length for the intake passages that serve each chamber which can be varied during engine running so as to be tuned for a wider range of speed and load conditions.
One way in which this is done is to provide at least two different length intake passages that serve each combustion chamber. The flow through these different length intake passages is controlled by a throttle control type of arrangement so that the effective length of the intake passage will conform to the optimum length for any given engine running condition.
These flow controlling throttle valves are in addition to the main flow control throttle valve which controls the total air flow through the system. In order to simplify the construction, it has been proposed to provide a common plenum chamber that is disposed in the valley between the cylinder banks and into which all of the intake pipes of the various lengths extend. This common plenum chamber has a common air inlet in which the main throttle valve for the engine is positioned. It should be readily apparent that this type of construction is very complex and places a large volume of components in the valley between the cylinder banks.
This type of arrangement places a large volume of the intake system in an area where a large amount of heat is also generated by the engine. Therefore, this type of induction system can experience deteriorated volumetric efficiency when operating at high temperatures.
It is, therefore, a principal object of this invention to provide an improved intake system for a V-type engine.
It is a further object of this invention to provide a tuned intake system for a V-type engine that is positioned in the valley between the cylinder banks but which will be adequately cooled and yet serve its intended purposes.